Capillary colloid



' Nov, 13, 1934. s. F. AGREE 'Y cAPILLARY coL'LoID MILL Original FiledSept. 11. 1924 2 Sheets-Sheet 1 NOV. 13, 1934. l s, F, AGREE 1,980,589

CAPILLARY COLLOID MILL Original Filed Sept. 11. 1924 2 Sheets-Sheet 2Patented Nov. 13, 1934 UNITED STATES PATENT ori-ics Applicationseptember 11. 1924, serial No. 737,209 Renewed June 27, 1932 s china.(ci. iis-14) (Granted under the provisions of lee. 14, act of March 2,1927; 357 0. G. 5)

art which have sought to accomplish these ends.

One of the objects of this invention is to produce processes which shallresult in stable suspensions and emulsions.

Another object of the invention is to produce machines which shallresult in such products and enable the carrying out of these processeseiliciently.

Other and further objects and advantages of the invention will appearfrom the more detailed description set forth below taken in conjunctionwith the accompanying drawings wherein there is shown by way ofillustration in Figure 1 a vertical transverse section through one formof the device; in Figure 2 a vertical longitudinal section of the deviceset forth in Figure l; and in Figure 3, a vertical section through amodiilcation of the structure shown in Figure 1. Figure 4 shows asection of one form of inlet and outlet, the rotor being in elevation.Figure 5 shows a modification, the rotor and casing being made up ofdiscs having complemental curvatine. Figure 6 is an elevation, partly insection, of a cone-type mill made in accordance with the presentinvention. But it will be understood that the drawings set forth thepreferred forms of the invention, and that various changes may be madetherein and in the processes set forth below, by those skilled in theart, without departing from the spirit and scope of the disclosedinvention. This invention is based on the following considerations. Whena liquid such as creosote oil, petroleum oil, etc., is passed underpressure through a capillary tube into another mutually insoluble liquidsuch as water, the creosote oil etc., constantly breaks off globulesfrom the stream or column of oil at the end of the capillary tube. Withdecrease in size of the capillary tube, the globules decrease in size sothat finely divided materials are obtained. Instead of using capillarytubes, a porous tube or plate (not shown) having a multiplicity ofcapillary openings may be employed, one or both of the liquids beingforced therethrough. For example the creosote oil may be forced throughone or a multiplicity of porous porcelain tubes at high pressure into asoap solution 'in order to form a creosote emulsion. The principaldisadvantage of such operation is that the capillary openings becomeclogged with solid or plastic materials, which it is diillcult toremove, as by reversing the pressure or by brushing. v

To avoid these disadvantages while retaining the desirable features ofsuch methods of disintegration, use is made in the present invention ofthe enormous centripetal and centrifugal forces obtainable at -highspeeds, such as 10,000 to 30,000 R. P. M. or even higher speeds, toforce particles of liquids, plastics, and solids into V shaped or othergrooves, which act as capillaries and in which the particles of liquid,etc., become longer and longer as they pass further into the V shapedgroove, with consequent diminution in cross section. As a result of suchdiminution in cross section, the particles become elongated like asausage, until they finally break up into two or .more globules of smalldiameter, which in turn pass deeper into the groove, the abovedescribed'A process being repeated automatically under the operation ofthe forces described above until the particles have reached a sizerepresenting the smallest division that can be obtained with the machineused. Where a series of connecting grooves are used, the material undertreatment is kept moving directly along such capillary grooves or acrossthem. While passing across them, the particles are part-A ly forced intothe groove and are broken up or cut" as indicated above, and then passon to the next groove to be further disintegrated.

It therefore follows that a part of the total liquid should have a speedhigh enough, at least at intervals, to sweep the suspended materialsalong the groove and thus prevent clogging. With the large pressureforcing or crushing the suspended materials into the grooves, it isclear that solids will be crushed into the V shaped grooves and thatplastics and liquids will act in the same way.

In a practical embodiment of this principle, the grooves may be ruledany chosen depth such as 0.1 millimeter (or 100 microns) and should bevery close together on both the seat and the cone of such mills as arereferred to above, or on the discs of the mills using such discs. Suchgrooves are shown in Fig. 6 and may be ruled radially or crisscross atany desired angles; or they may be cut into the seat or the cone or discto correspond with the path of a suspended particle in the solutionpassing through the machine, or at right angles or other angle to suchpath, in order to get maximum shear. Each of these rulings has certainadvantages, but it is very important for the best results lo place thegrooves very close together, such as 0.1 to 0.5 millimeter or lessapart. and to make them of fairly uniform depth. The position and angleof the V shaped groove or other form of groove when used. should be sorelated to the surface that the pressure forcing the particles intothese grooves should produce the greatest possible rupture of theparticles.

Another method of using such capillary forces in these grooves is toemploy a grooved cylinder rotating at high speed in the correspondinggrooves of a circular or helical or other form of casing and to run theliquid and suspended material into and radially around and out of therotor and casing. Considering the path of suspended liquid or solidparticle it is seen that at high speed such as 20.000 R. P. M., themachine acts like a centrifugal pump and that the centrifugal forceexerted is very great. Hence even small differences in specific gravitybetween the suspended particles and the suspension medium are highlymagnified with the result that the suspended particles heavier than themedium are thrown outward into the grooves of the casing with greatcentrifugal force while those particles lighter than the medium areforced inwardly into the grooves of the rotor. These centrifugal andcentripetal forces cause the suspended particles of the liquids orsolids to be forced into the V shaped grooves where the cross sectionsare made smaller as discussed above. The current of liquid always movesalong the groove to sweep it free of material that might cause clogging.As the laws governing bodies falling in a fluid apply to thesecentrifugal forces, the heavier or larger particles of a given materialare thrown tangentially outward when such material is heavier than thesuspension medium and are therefore crushed in the V shaped grooves ofthe case, the smaller particles being more easily kept in suspension byconvection and the lower rate of outward movement or falling. Hence thelarger particles have always the largest number of chances of beingthrown into the capillary grooves and of being crushed into the smallestparticles. The same applies to the particles lighter than the mediumwhich are thrown inwardly into the grooves of the rotor where they aredisrupted.

There are conditions under which the centrifugal and related forcesexerted in any given material under treatment is small. For example, ifthe specific gravity of an organic oil in suspension is practically thatof water, used as a medium, the centrifugal separation may be small.Several methods may be used to modify such conditions so that advantagemay still be taken of these centrifugal forces to produce the resultssought as outlined above. In one such case, since as a general rule theorganic substances have a coeilcient of expansion of 0.001 while that ofwater is 0.0001 per degree centigrade, by heating or by cooling themixture great differences in the specific gravity and the dispersion ofthe materials is obtained. Furthermore, heating often causes hydrationof a suspended material which weakens the cohesive forces, so that theparticles are more easily dispersed.

Another method that may be used in varying .the factors that enter intoand control the dispersive conditions, is to control the electrochemicalconditions of the mixtures, etc., so that the particles of the materialsundergoing dispersive treatment are given high electric charges andmobilities and contact potentials toward the dispersing medium. In suchcases the rotor and the case within which it revolves may be used as theelectrodes, and under the influence of the chosen electrical conditions,the charged larger particles are forced against the case (or rotor) toaid in the disruption.

In any such modifications, or any case coming within the scope of thisinvention, when it is desired to use a solvent for example like carbondisulphide, carbon tetrachloride. etc., to dissolve a material likesulphur, etc., and to disperse the resulting solution in water, whichmay contain a stabilizer such as soap. galaetan, glue, etc. if desired,followed by distillation etc. to recover the solvent and to leave thedissolved substance in colloidal dispersion, the solvent may be chosenwith a desired specific gravity, i. e. heavier or lighter than water, sothat the particles are forced outward or inward as desired and disruptedby the case or rotor and their adjacent regions of shear in thetraveling film of material.

It is of particular advantage to change the tangential movement andthrust of the particles each moment by the curvature of the case and therotor to assist in the disruption. By increasing the rate of flow of theliquid through the machine by the rotor itself or by means of an outsidepump, the greater this thrust, becomes, and the more the particles areforced into the grooves as they are ldiverted from the tangential to theradial or circumferential movement in a plane substantiallyperpendicular to the shaft and hence the more efficiently they aredisintegrited or dispersed; this fact is true of no other rotating millof which I am aware and constitutes a highly useful novelty of myinvention.

In the annexed drawings, Fig. 1 is a vertical cross section of a millhaving a horizontal inlet and outlet, and Fig. 2 is a verticallongitudinal section of a portion of the length thereof, on the line 2-2of Fig. 1. Fig. 3 is a cross section of a modified construction showingvertical inlet and outlet. Fig. 4 is an elevation, partly in section ofanother type of mill, the rotor being il shown in elevation with finegrooves on its surface and having a tapered inlet pocket. Fig. 5 shows asection of a mill in which the rotor and casing are grooved with shallowrounded grooves.

Fig. 6 is a different type showing a cone and conical seat adapted forspray drying.

In the embodiments illustrated in the Figs. 1 and 2 of drawings asexemplary, there is shown a grooved rotor 1 with grooves 2. the rotorbeing adapted to run at speeds from 1000 to 20,000

R. P. M. or even higher, within a grooved casing 3. The rotor ispreferably mounted eccentric to the casing. The outside diameter of thetongues 4 0f the rotor is larger than the inside diameter of the tongues5 of the casing. The angular relation of these tongues is important inconnection with the capacity of the machine. If the angle of the tonguesis 60, the width of the film and the capacity of the mill are just twicethat obtained when the rotor is cylindrical and contains Ill no grooves,but is the same distance from the case as set forth below. If the angleis 30, the Width of the lm is about four times that of the smooth rotor.The capacity of the machine increases with decreasing angle of thetongues.

At one (or both as desired) end of the shaft 6, there is preferablyplaced a thrust ball bearing '7, in a threaded seat 8, to enable therotor to be moved longitudinally` as shown in Figure 2. The purpose ofthis arrangement is to allow variation in the distance between thegrooves and tongues on the rotor and the tongues and grooves on thecasing. If desired, a governor may be arranged on the shaft to keep itse'nd pressed tightly against the ball bearings and hence keep the rotorin a fixed longitudinal position. Or one or more collars placed on theshaft may rotate in connection with ball bearings, the longitudinalposition of the bearings and collars and hence of the rotor and shaftbeing adjustable and then held fixed.

The casing 3 is attached to the base plate 9. the latter being. adaptedto slide on the plate 10 by means of a well fitting tongue 11 and groove12, or other similar arrangement on the base plate 9, the movement thusobtained being transverse to the axis of the rotor shaft 6. In Figure 1,the left hand side 13 of the casing 3 can be bolted above and'below asby bolts 14 and 15 to the right side 16 of the casing 3. The left handside 13 may also be arranged by means of a tongue 17 and groove 18, toslide on a special or secondary base plate 9. In the modification setforth in Figure 3, each half of the case 3 may slide on itsv own baseplate 9'.

A screw arrangement 20 (or an equivalent lever or wedge or otherarrangement) may be used to permit sliding of the casing as a wholerelatively to the rotor, so that the distance between the rotor an'dcasing may be varied for any desired purposes. As shown in Figure 3 thetwo halves of the casing may be moved independently.

'I'he casing 3 is preferably made hollow as shown at 21, 21, 21 inFigure 1 and at 21', 21' in Figure 3, to enable the introduction of acooling or heating medium, for example, brine for cooling, or steam, hotoil or water for heating etc.; or one side may be heated while the otheris being cooled, depending on the results which it is desired toproduce.

The two halves of the case are usually divided in a vertical plane whichpermits easyunbolting and replacement of the gaskets 2'7 or 27' when thelatter are used between the halves of the casing, and also allows easyseparation and cleaning of the rotor and the inner walls of the casing.The tongue and groove arrangements on the bases also facilitate thereassembly of the machine with proper alignment of the tongues andgrooves on the rotor and the inner walls of the casing. While thisrepresents the preferred form of the machines, the latter may have itscasing divided horizontally or it can be made in three or more parts asmay be desired without materially affecting the machine as illustratedand without departing from the scope of the present invention.

The rotor 1 may be cast solid or integral with the shaft and thenmachined. 0r it may consist of a cylinder machined true on both theinside and outside to balance when used at high speeds; in which casethe ends of the rotor may consist of two discs with left-and rightthreads respectively to screw onto the shaft and into the inside of theends of the cylinder and against shoulders therein to prevent turning ofthe cylinder with reference to the ends and shaft while in use. Properkeys and threads hold the ends and shaft rigid, and the ends may beperforated if desired. Keys may also, pass through the threads betweenthe ends and cylinder.

The inner surface of the oase may be cast integrally with the case; butit may also be made as a solid or split sleeve with outside circulardiameter permitting it to slip into a corresponding circular openinglengthwise the case. If this circular opening in the case and the rotorare eccentric. as well as the outer and inner 4surfaces of the sleeve, arotation of the sleeve within the case will vary the distance betweenthe rotor and various points on the inner surface of the sleeve asdesired. The sleeve can be keyed to the inner surface of the case topreserve these relative positions. These removable sleeves have theadvantage that they may be readily replaced when worn, may be cleanedreadily, and may be changed for others with different inner surfaces fordifferent uses. The outer case may then be in one piece. When the rotoris a plain or ruled cylinder the sleeve need not be split.

As shown in Figures 1, 2, and 3 of the drawings, the distance betweenthe grooves of the rotor and casing gradually diminishes from the inletto the outlet, from say about 0.1 to 0.001 inch,'so that largersuspended particles entering the mill are continuously disintegrated asthey flow around the rotor. This graduated spacing is accomplished bymachining the grooves in the left hand side of the ease with any desireddiameter larger than that of the rotor and of the grooves of the righthand side of the casing, the latter being closer to the surface of therotor itself. As these machines are best made in standard sizes, theleft halves can be bolted together and machined to make the grooves asdesired, particularly so that the grooves at the lower portion of theright hand side of the casing will form a continuation of the grooves atthe lower portion of the left hand side of the casing, when the twohalves are assembled. By the arrangements shown in the drawings anddiscussed above, the distance between the rotor and the portion of thecasing nearest to the rotor, can be adjusted as desired. Two righthalves of the casing can also be bolted together to machine the groovestherein with any desired diameter compared with those of the rotor. Theright half of the casing shown in Figure 3 may have exactly the samediameter for the grooves as has the rotor. Or the diameter may beslightly larger with the diierence used as spacing between the rotor andcasing at the bottom, the top and upper right hand sides of the rotorand casing fitting very closely. These same methods are used with theplain cylinder rotors and casing described below.

In Figure l there is shown an inlet 22 and an outlet 23, formed by meansof openings 24 and 25 in the right hand portion of the case, the inletpreferably containing a strainer (not shown) to prevent the entry oflarge objects, and while these inlet and outlet openings may be of thesame size, it preferable to make the outlet somewhat larger in diameter.'I'he upper portion of the right hand side of the casing is prefer-`ably separately machined to form a continuation of the grooves in theleft hand side of the casing. That portion of the right hand side of thecasing which lies between the inlet and outlet openings preferably fitsvery close to the rotor so that no liquid may pass into the inlet afterthe material has passed around the rotor, For similar purposes thatportion of the casing between the openings 22? and 23 shown in Figure 3is similarly placed close to the rotor for similar reasons. If desiredthe portions of the casing 26 and 26 respectively in Figures 1 and 3 maybe made as separate plungers, rectangular or otherwise in shape, fittingclosely to the rotor and arranged with springs and levers or wedges orscrews at one or both ends or the center thereof,

to press the portions or gates 26 or 26' against or 150 as near asdesired to the rotor to allow for variations in the position of therotor when adjusted as set forth above. The centrifugal force exerted onthe particles of the material under treatment causes practically all ofthe liquid to fly off the rotor into the outlet, while the liquidentering through the inlets cannot, even when under pressure easily flowunder the gate because of the opposing pressure exerted at the highspeed. The outlet may advantageously have a baffle 30 running its lengthas shown in Figure 3 and so situated that the liquid flying from therotor at high speed strikes the baille and causes disruption of theparticles by the impact. -The two halves of the casing may be separatedby a gasket of paper, metal. or other material as shown at 27 and 27',of any desired thickness, and by variation in the thickness the distancebetween the rotor and the case may obviously be varied. For furtheradjustment, the case or either half thereof may be raised or lowered bymeans of screws, wedges, 0r shims, placed under the halves of the case.By these means. the case can be Separated as desired from the bottom,sides or top of the rotor.

The roller or ball or other bearings fcr the shaft may be housed inseparate standards outside the case as illustrated in Figure 2; or itmay be cast or made integral with one of the halves of the case, as onthe right side of Figure 1 where the distance between the rotor and casemay be advantageously fixed. But the bearing housing may be adjustablein position if desired to space the rotor from the bottom, sides, endsor top of the case.

Another feature of the disclosed machines 1s that they may be used aslow speed grinding mills. In this connection attention is called to thefact that in making the very perfect nuts and screws for ruling engines,dividing engines, etc., the split nut can be run backward and forwardover the rotating screw with a proper cutting lubricant whereby thethreads can be made to fit so perfectly that longitudinal movements andmeasurements within about 0.000,01 millimeter may be made. By employingthis principle of machine cutting, the grooves in the case and rotor maybe made to fit each other very closely, and by then pushing the desiredportion of the case against the rotor while the latter is rotating, andemploying suitable grinding and lubricating materials, the surfaces ofthe grooves can be made to t each other as perfectly as desired. Inother words, the grooves in the machine are self grinding or selfadjusting over the entire length of the case 0r rotor. In an analogousmanner the right hand and left hand portions of smooth casings may bepressed against a smooth rotor, and with the use of proper lubricantsground to fit as closely as desired. 1n all of these cases, theparticles passing through the mill receive the same degree cf grindingaction with consequent dispersion. The amount of heat generated by thefriction of the rotor against the case is small and this friction may beprevented from generating much heat by placing a cooling medium in thejackets.

The mills referred to above may be made of any desired material suitablefor the particular purpose in hand, such as hard steel, Monel metal,brcnze, etc., and the rotor or case or both may be plated with tin,lead, gold, silver, etc. when desired.

In place of using castings for the rotor and case, each may be built upto any length by using sheets of any desired metal to stamp out circulardiscs d with perforations to decrease the weight when desired and withcentral openings for slipping them over the shaft to make a built uprotor.

and stamping out corresponding cross sections cof the entire case tomake a built up case as shown in Fig. 5. Threads and lock-nuts 1n on theshaft hold the circular discs tightly together like a cast rotor. Thecross sections of the entire case have openings to make annular passagesthrough them through which threaded bolts b pass to hold the sectionstogether. By the use of proper openings for the inlet and outlet pipes.and for cooling or heating jackets. with the use of proper end plates,al1 as will be understood by those skilled in the art, the entiremachine may be assembled simply, to replace the castings referred toabove. The advantage of this method of construction is that the lengthof the parts may be increased to give greater capacity, while anysections that become worn or broken may be simply replaced. Further themachine may be easily disassembled for cleaning etc. When acomparatively smooth rotor is desired the d ses will be cylindrical. Butwhen the rotor and the inner face of the case are to be V or sinegrooved and have the relative features set forth in the drawings, theouter edge of each section of the rotor and the inner edges of thesections of the case are made to give the desired grooves whenassembled. These grooves will be so arranged that the structuredescribed above with cast sections in Figs. 1, 2 and 3 is obtained.There will be no need in this type of structure to have the casing intwo or more portions as is necessary when castings are used.

The rotor shaft may be integral with, or directly connected by aflexible coupling or by a belt or gear drive to the shaft of a steam orair turbine or an electric motor. The rotor can operate eitherhorizontally or vertically with efficiency. The larger mills for factoryuse with rotors 10 to 20 inches in diameter may be operated at speeds of5000 to 10,000 R. P. M. with safety, while smaller mills may be run ateven higher speeds for example from 10,000 to 20,000 R. P. M. for makingdispersions of vcastor oil, milk powder, mayonnaise, malted milk, orother useful colloidal solutions and dispersions.

As indicated above, a modification of the machines set forth above isobtained by omitting the grooves in the rotor and case and therebyconverting the rotor into a cylinder rotating within a case which iswholly or partially cylindrical and whose inner surface is eitherconcentric with the rotor or has a varying position relative to thesurface of the rotor, as shown in Figures 1 and 2; for example, adecreasing distance when passing from the inlet to the outlet. Largerparticles coming into the wider clearance are crushed into finer oneswhich pass on further and are crushed again and finally by attritionamong themselves and against the walls and between the liquid lms arebroken down into colloidal size. A distinct addition to theeffectiveness of such action is provided by sand blasting or rulinglines on the rotor and case either parallel to the axis of rotatlon,crisscross as in Fig. 6 or spirally as in Fig. 4. These lines may be ofvarying depth and distance apart such as from 1 micron to 0.001 inch ormore. And the relation of the width of the grooves to the depth, as wellas the angles made between the sides of the groove and a radius drawn tothe bottom of the groove, can be varied at will to suit the particularsubstance which is to be broken down into colloidal condition.

When, as in Figure 4, the rotor and case are concentric, the case orrotor or both may be conlcal for about one inch, and the surfaces may besmooth, roughened, grooved, or ruled. The liquid may be forced throughby a suitable pump and will pass in at the one end i, spirally throughthe machine, and out at the other end O. The liquid is thus subjectedfor a longer time and distance to the centrifugal and disrupting forceswith resulting greater disruption. Since in the ordinary construction,the inlets .and outlet extend for the same length more or less as therotor, if desired, one portion of the inlet may be closed, and acorresponding portion of the outlet closed, so that the liquid musttraverse a spiral path through the machine by entering and leaving theends, where for example the case or rotor or both are conical as in Fig.4, thus increasing the disruptive action due to the increase in timethat the material will remain subject to the action of the mill.

One marked advantage of these different embodiments of the capillarycolloid mill is that the enormous centrifugal forces always throw theliquid outward into the casing and that the liquid does not flow out atthe ends of the casing and rotor. With the grooved rotor and case, theliquid nows in the grooves and with the smooth or ruled rotor and case,a small shoulder in Fig. 2 causes any film escaping between suchshoulder and rotor to be thrown outward until it reaches the outletf Ifhowever the liquids are forced into the mill to increase the capacity,sunicient pressure can be applied to force the liquids out at the end ofthe rotor and case and in such event, end plates p are attached as shownin Figure 2 to prevent loss. 'Ihe use of soft gaskets in a stuning boxb, allows the case to be moved in the bed plate grooves a few hundredthsof an inch, which is sufncient for making the require'd adjustments as ageneral rule. l

When the liquids are pumped through the mill with increased velocity toincrease the capacity, there is also increased kinetic energy in thesuspended particles as they strike the containing wall and hence greaterdisruption. While forcing the liquid through the mill, the rotor may beturned in a direction opposite to the flow of the liquid, therebyproducing greater disruption but smaller capacity.-

If still greater centrifugal and disruptive forces are desired, than arepractical by increasing the speed and diameter of the rotor the case canalso be made to rotate oppositely to the rotor. The case bearing can bearranged on the shaft of the rotor or the rotor and case may each havetwo or more bearings on one side. The inlet and outlet of the case mayconveniently connect with a hollow shaft, equipped with portholes andreceiving slip collars for allowing liquid to flow in and out throughthe nlm space.

This colloid mill can be used not only for making colloidal solutionsbut for spray drying of similar solutions or other materials, and thisis one of the novel features of the present invention, particularly formaking dry colloidal powders. By leaving the cap on of the outlet of themill in Figs. l and 3 the colloidal solution will emerge in the form ofa very nne spray or mist, each little drop of which containscomparatively few colloidal particles. By passing this mist, preheatedwhen desired, into a vacuum, or into a. stream of heated air or otherfluid, in closed chambers the liquid is evaporated and the few colloidalparticles form a small mass. The colloidal solution and the driedcolloid powder may or may not have added to them a stabilizer orprotective colloid such as galactan, gum Arabic, glue, etc. Milk, fruitjuices, colloidal polishing materials, colloidal dyes, rubber latex, andnumerous other materials as well as mixtures containing them, may bedried in this way. For example sulphurcarbon disulphide solutionsdispersed in water, can well be made up in this way. The colloidalpowder is collected in settling chambers or by means of screens or byelectrical precipitation and the evaporated solvent may be condensed outof the air stream by cooling coils, etc., the air again being usedcyclically in the process. When the colloid powder is glutinous likedispersed rubber-sulphur-accelerator-pigment mixtures, the settledpowder may form a cohesive mass. But when the particles are surroundedwith a stabilizer, such as milk powder, the colloid mass may be shippedand then` taken up in the solvent and dispersed again, especially withthe colloid mill.

But the use of these high speed cylinder and cone type colloid millsherein set forth are particularly claimed in making colloid spraydryers. By omitting from the China and Fornander and similar cone millsthe housing used to receive the colloidal solution after it passesthrough the nlm space between the cone and its seat, the nlm ofcolloidal solution is thrown into the air as a mist as in Fig. 6. Such acone mill for spray drying should be preferably provided with thebearings and shaft on one side of the cone only, and the solution shouldnow from this side through the film space so as to emerge into the openair as a hollow cone of mist without striking any further parts of thecolloid mill. Running air at a with the liquid at i through the nlmspace gives a nner mist and smaller colloid masses.

This type of spray drying gives a fine product and the capacity is muchhigher than is obtained in spray driers containing single small orincesthrough which the liquid is pumped at high pressure into a heated airstream.

Although this principle of capillary colloiding gives highly dispersedcolloids comprising liquids, waxes, and solids, it has been found to beparticularly desirable to combine such processes with the regulation ofthe physical and electrochemical properties of the solution such asviscosity, surface tension, and concentration of hydrogen, hydroxyl andother monoand polyvalent anions and cations such as sulphate, phosphate,calcium, and aluminium, in order to nx the nature (positive or negative)and extent of the electrical charges on the colloid particles, theircontact potential difference toward the solution, their mobility andtheir tendency to repel each other and remain stable or to come togetheror nocculate into larger masses of colloidal particles which settle outof solution. By the use of hydrogen electrodes, cataphoresis apparatus,and buffer materials etc., I can easily regulate all these factors andhence the properties of the colloid solutions and make them remainstable indennitely with the particles in vigorous motion or pass throughvarious smaller degrees of stability and mobility and finally losepractically all electrical charges and motion, and nocculate out.Portions of the colloidal particles may be nocculated fractionally, orall of them may be nocculated, and the solution clarined.

The properties of these solutions can hence be regulated as desired withreference to other colloidal or true solutions with which mixtures areto be made. In particular the colloidal particles may be chargedpositively or negatively and given mobilities from practically zero toas much as the usual anions and cations of elements or compounds(excluding hydrogen and hydroxyl ions); namely about 3-7 microns persecond per volt centimeter drop in potential when electrolyzed at about25 C.

This colloid mill is highly efficient for disruption of liquids, waxes,semisolids, occulated masses and solids suspended in aqueous andalcoholic liquids, petroleum, and other liquids. The particles may bevaried in size with the different materials, depending upon theintensity of the forces applied, the distance between the rotor and thecase, the volume of the material passed through the mill per hour, andthe electrochemical conditions of the solution. But the particles can bemade small enough in general to show Brownian movement and vary fromabout one micron (0.001 millimeter) in diameter downward, while all ofthe particles exhibit uniform electrochemical properties. This mill isefiicient for changing an oil-in-water emulsion to a water-inoilemulsion with change in the electrochemical conditions of the solution.It is suitable for intensive mixing of insoluble materials; e. g. tnedispersion of coal in crude 'heavy petroleum oils to make a liquid coalfuel, or graphite in lubricating oil, or the re-dispersion offlocculated aluminium hydroxide which can be broken up into thecomponent colloidal particles in oil-inwater emulsions or Western larchgalactan-tannin extracts and allowed to reflocculate at a hydrogen ionconcentration of about P11258 and bring down the oil or tannin materialsand clarify the (galactan) solution. It is useful for intensive mixingof alkalies or acids with oils from which acid or alkaline constituentsare te be extracted and settled olf in the aqueous solutions. It issuitable for treating old newspapers with oils or clays like bentonitein water to de-ink the paper while separating the fibers and renderingthem suitable for making paper again. It is useful for intensive washingof impurities from very small crystals by means of suitable solvents,the small crystals then being separated out by a gravity centrifuge orfilter. It is especially useful for disintegrating slowly solublematerials in a liquid into extremely ne particles which dissolve morerapidly. By having two or more inlets any given mixtures can be formed,such as a colloidal precipitate from two true solutions which can thenbe intensively mixed with another material such as a protective colloidlike galactan for stabilizing the first colloidal precipitate. Anynumber of consecutive reactions of true or colloidal solutions can thusbe made to take place at desired very short time intervals. 'I'hemechanical, chemical, and electrical forces taking part in theseprocesses are rigidly controlled by these methods.

The mills described above as a feature of this invention present manyadvantages over known mills. The liquid leaves the disrupting region ina film whose cross section parallel to the shaft is a straight or acorrugated line which may strike a baille plate in the outlet at highvelocity and disrupt the suspended particles still further. This linemay be as long as desired and therefore increase the area and capacityof the single opening of the Gaulin homogenizer.

This mill is so arranged in Figs. 1, 2 and 3 that the line of flow ispractically always in a plane perpendicular to the shaft. As a resultthe centrifugal forces and the forces (kinetic energy) causingdisruption which come into play when the path of a particle iscontinuously diverted from the tangential to the radial orcircumferential are all in a plane perpendicular to the shaft andtherefore at a maximum. The case may be regarded as having acomparatively very thin liquid film on its surface and the rotor ashaving a film on its surface which move with high velocity past eachother, and the intervening liquid. Such liquid films passing at highvelocities such as 2 to 4 miles or more per minute act almost like solidgrinders causing disruption of liquids, waxes, solids, networks offibers, and crystals, etc., thrown by the convection currents andcentrifugal forces into the regions of film shear without contaminatingthe solution with abraded particles of the mill metal.

The V or other shaped grooves act like capillaries when liquids orsolids are squeezed into them by the centrifugal forces and suchsuspended material is thereby elongated and diminished in cross sectionand disrupted into smaller particles. This process is continued untilthe finest of subdivision is accomplished. The kinetic energy of thesuspended particles given by the centrifugal and pumping forces causeseach particle to be jammed or squeezed unto the V or sine or othergrooves when the path of the particle is diverted from the tangential tothe radial or circumferential. As the high speed liquid traveling in thegroove sweeps these jammed particles along, a multiplicity of suchjammings or impacts take place continuously around the case and causehigh dispersion of the suspended particles.

The minute disintegration of solids or liquids in liquids brings aboutintimate contact and mixing and reactions otherwise requiring too muchtime and material. This mill is therefore useful, especially withelectrochemical regulation, in all of the following classes ofprocesses.

Carbons. clays, cellite, silica gel, etc., are dispersed in turbid, oilyor aqueous solutions requiring clarication, reach all particles thereofefficiently in a way not possible with coarser decolorizing materials,and upon proper electrical regulation occulate out with the impurities.

Different types of china and ball clays, flint, feldspar, etc. can behomogenized and converted into uniform mixtures for the pottery or tilemanufacturer.

Photographic emulsions, mica colloidized with rubber and paraine orother waxes to form a dielectric for condensers, and rubber andparafline and vaseline dispersions for condensers and lubri- 1f cantsand salves are easily made.

Carbon black with or without added dyes may be homogenized in oils tomake printers ink.

Flavoring extracts and perfumes are dispersed and dissolved in alcoholicand aqueous suspensions.

Powdered milk with or without added butter fat or oleomargarine, oils,etc., gelatine, albumin, etc., may be homogenized into milks and creamsand icecreams, together with dispersed air when desired.

Various hydrogenated and natural vegetable and animal oils may bedispersed hot and cooled quickly to form homogeneous lards and butters.

Malted milks, chocolate, orange flavors and other materials may bedispersed to form soda fountain drinks.

Oxides of magnesia, zine, aluminum and the like are simultaneouslydispersed and hydrated to form milks or creams.

The homogenization of immiscible liquids such as aqueous or acid oralkaline solutions and benzol, gasoline, creosote, rancid peanut oil andvegetable oils, allows washing and removal of acids, bases and otherimpurities or constituents which may be recovered.

The intensive mixing of crystals containing adhering oily or solidimpurities with solvents capable of dispersing the impurities intocolloidal solution leaving the crystals pure is carried out in this millwith great emciency.

Dispersions of paints and stains in oils or water with stabilizers suchas suspensions of zinc oxide. barium sulphate, lead oxide, leadsulphate, iron oxide, whiting, etc., and organic dyes and stains inlinseed oil, sh oils, creosote, etc., or in water with stabilizers suchas glues, albumins, galactan, etc., are suitable for painting andstaining woods, shingles, metals, etc.

The dispersion of nitrocellulose, cellulose esters, natural and articialgums like damar, kauri, coumaron and also appropriate coloring mattersin solvents like ketone oils, amyl-acetate, diacet-one alcohol, ethylacetate, benzol and mixtures thereof make excellent lacquers, varnishes.etc.

By using albumins, glues, dextrines, western larch galactan, gum arabicor other protective colloids like oleic acid compounds, sulphonatedanimal or vegetable oils or other stabilizers with regulatedelectro-chemical conditions and employing water, animal or vegetableoils, organic or inorganic solvents, etc. a wide variety of dispei-sionsuitable for foods, fuels, cleaning agents, medicines, industrialsolvents, etc., may be made, such as mayonnaise dressing, graphitesuspended in lubricating oils or emulsions thereof, colloidal coaldispersed in fuel oil with a stabilizer, liquid soaps, colloidal inks inoils or water, shaving creams, tooth pastes, ointments of all kinds,vaselines, leather and belt dressing, etc.

The mill is excellent for the disruption of masses of ne or colloidalparticles like clays, diatomaceous earth, fullers earth, iron oxide,chalks, maris, rouge. ores in mineral flotation, cement, cellite etc.

'I'he mill disintegrates, and forms aqueous, alcoholic, or oily extractsof, vegetable cells like yeast, bacteria, starch, plant tissues like tanbarks and woods, lemon peel, ginger, cinchona bark, coee, etc. Thefibres or cell walls settle out and leave the extracted materials incolloidal suspension. If desired the pH value and other electro chemicalproperties can be regulated so as to flocculate or dissolve any portionsof the extracted material or of added constituents and form extracts ofdesired properties such as invertase from yeast.

In the same way extracts can be made oi' all kinds of meat tissues, etc.in the cold without coagulation of proteids or in hot solution involvingsuch precipitation.

Emulsions of castor oil, cod liver oil, mineral oil, olive oil, maltedmilk, and many other mediciv nal suspensions with stabilizers are easilymade.

Dispersions of waxes such as paraine, rosin, beeswax, carnauba wax,ozekerite, asphalt, pitch, and the like are made in this mill and usedas waterproof coatings or sizings for paper, cloth, linoleum, concretewalls, walks, floors, roads, etc.

Insecticides, fungicides, and disinfectantsare made by forming colloidalsuspensions of calciumA or other arsenates, Paris green, Bordeauxmixture, creosotes, etc., with stabilizers or oils or both at pH 8 or 9for example and using them as sprays or dips lfor plants or animals orcross ties, poles. posts, etc.

The niill can be used for beating pulp to separate the libres and washout the pulping chemicals; for disintegrating old newspapers and otherwaste paper with solvents or bentonite under regulated electro-chemicalconditions to remove ink and oils from the ,bres which are therebyconverted into a pulp stock suitable for use again: for the uniformbeating and mixing of rag stock; for the uniform dispersion of therosin, barytes, casein and other constituents of paper sizing underelectro-chemical regulation such as at pH value about 8 to 9 to keep thenegative rosin and other colloidal particles in active Brownian motionancl` stability while making and keeping the sizing and yet allowingthese particles to precipitate out on and coat the paper fibresuniformly when applied thereto in the paper making machinery.

The mill can be used for softening old rubber tires, or other wasterubber, with a solvent like naphtha and dispersing this softened rubberin water with a regulatedgstabilizer like albumins, gums, casein, glues,soaps, etc., separating the rubber emulsions from any fibres, andheating this artiilcial latex or emulsion with 5-10% alkali at -150pounds steam pressure 5-25 hours to remove sulphur and devulcanize orreclaim the rubber, which is precipitated and then washed free of thechemical solutions. The alkaline liquor is evaporated, incinerated,dissolved, limed, ltered and treated to recover and reuse the alkali.The mill may be also used to homogenize the artificial or natural rubberlatex with sulphur, iron oxide, antimony sulphide, accelerators, carbonblack, zinc oxide, etc., under regulated electrochemical conditions suchas at pH 9 and with colloid mobilities from 4 to 6 microns per secondper volt-centimeter drop in applied E. M. F., and then vulcanized insolution and spray dried or coagulated, or first spray dried orcoagulated and then vulcanized, and used for making rubber articles.

'I'he mill can be used for making clay castings 120 and reclaiming wastecastings by regulation of the electro-chemical conditions as follows.The

clay mixture is roughly disintegrated into about 25 mesh material anddispersed in this colloid mill or broken up in a grinding mill in water1'25 into a uniform suspension. 'Ihe pH value and colloidal mobility mayvary with the kind of clay used, with its tendency to change from thesol to the gel form, with the details of the processes employedsubsequently, and with the objects to be made. pH values 7.4 and 8.0represent those used in this process in two plants. By adjusting thisclay mixture with acetic or other acid, or with an alkaline carbonate orhydroxide if necessary, itis easy to get a pH value best suited to thesubsequent work. This adjusted clay suspension is then screened toremove larger objects, and then lter-pressed to remove the water down toaround 22-30 per cent. 'I'his wet clay is then treated with the feldsparand flint if these were not added originally and with sodium silicateand alkali to form a clay slip containing about 22-30 percent of waterand having a pH value such as 7.5 to 8.5, depending upon the clayandfurther use. 'Ihis slip is largely in the sol form and drains and flowsreadily and is run into plaster of Paris or other moulds to remove waterand other soluble constituents and form articles such as wash bowls,electrical xtures etc. These partly dried objects are allowed to standor are passed through 1:3

heated drying rooms to dry thoroughly and set the clay gel and are thenbaked. During these processes the castings often crack and causeconsiderable financial losses unless the above electro-chemicalconditions have been regulated properly, and there may be further lossesin the subsequent stages of firing and glazing. By such electro-chemicalregulations a higher plant yield of objects of better color, toughness,and durability can be obtained. By'these processes it is possible to usethe waste clay castings. It is only necessary to use these castingsalone or in mixture with fresh clay and grind them together Whileregulating the pH value to the desired point by adding acetic or otheracid to change the set" gel back to the sol form and to adjust thealkalinity arising from the silicates and other basic materials in thewaste clay scrap. In this electro-chemical regulation the alkalinity ofboth the water and of the waste or fresh clay varies so much that theaddition of fixed quantities of acid for all clays and water will notsuffice; sufficient must be added gradually to give the definite desiredpH value to each plant batch when tested properly by colorimetric orelectrometric methods. By the use of these processes uniform potterypractice may be had even though the water and the exact composition ofthe clay and clay scrap may vary from time to time and cause difcultieswithout such electrochemical regulations.

This mill is especially useful for forming an emulsion of a preservativesuch as a creosote from coal tar, wood tar, or water gas tar. By passinga mixture of creosote and a soap solution of '1-5 percent of rosin soap,sulphonated sh oil or castor oil soap or other stabilizer, through themill while adjusting the pH value of the finished product to 8.5 to 9.5the creosote is dispersed into particles all of which are in vigorousBrownian motion and with diameters 1-2 microns or less and withstability and a mobility of about 5-6 microns per volt centimeter E. M.F. at 20 C. This creosote can be boiled or frozen without appreciableocculation. The percent of creosote in the emulsion may vary widely, sayfrom 1-95 percent. It can be used with very great advantage and economyin replacing straight creosote for impregnating ties, telegraph poles,paving blocks, timbers and the like by spray, vat or pressure cylindermethods. For example, by compressing air into the dry ties in a,pressure cylinder at 15 pounds and then forcing the hot creosoteemulsion under 100 pounds pressure into the ties, the creosote particlespenetrate several inches into the wood and are deposited on the fibrewalls and coat them thoroughly to prevent the growth of fungi andbacteria therein. The aqueous suspension medium and residual creosoteparticles are forced out ofthe ties by the compressed air therein whenthe pressure is slowly removed from the cylinder and the creosoteemulsion is pumped out. By applying a vacuum gradually to the cylinderthe last portion of the emulsion is removed from the wood. Thisrecovered emulsion is used for dispersing more creosote therein whendesired. Obviously the variations in the technique can be used tocorrespond to standard practices in individual plants. The ties areallowed to air dry or may be kiln dried to remove the water withoutcracking and are then ready for use. Obviously this emulsion may be usedto treat other porous materials such as concrete walls or piles orblocks and the like, the pH value being properly adjusted not to injurethe concrete while at the same time causing the deposition of thecreosote particles. The creosote may be mixed with toxic materials likecopper arsenate compounds, zinc chloride, sodium fluoride, chlorinatedphenolic and amino compounds, coal tar, bitumen, asphalt or otherdesired ingredients which are thoroughly dispersed with the creosoteparticles in the emulsion. The treatment with the creosote may also becoincident with or alternate with water proofing, fire proofing orrubberizing or other treatments to give the wood, concrete etc. otherdesirable qualities. For example, a mixture of creosote and natural orartificial rubber latex can be made as a stable emulsion with colloidalsulphur and an accelerator to vulcanize the rubber after it is depositedon the cell walls with the creosote, the treated wood being therebypreserved, Waterproofed and toughened. Solutions of borates, phosphates,arsenates and the like can be forced into the wood as a part of orseparate from the creosote emulsion and after the removal of thesesolutions from the wood another solution containing compounds ofaluminum, copper, zinc or other desired materials can be injected intothe wood to form insoluble fire proofing, disinfecting, borates,arsenates, hydroxides and the like which coat the wood fibres. Theexcess solution is then removed from the wood. By adjusting theelectro-chemical conditions properly fairly stable colloidal suspensionsof such' insoluble borates, arsenates, and the like can be made with themill and then injected into the wood and allowed to floceulate out onthe wood fibres, the excess solution then being pumped from the wood asdescribed above.

By way of illustration of the methods of electrochemical regulation ofsolutions, mucic acid can be chosen as a buffer material. When treatedwith alkali to give increasing amounts of the acid salt and then of theneutral salt per molecular weight of mucic acd in a given volume ofsolution, there is both a decrease in hydrogen ion concentration, CH, orincrease from say 3 to 6 in pH value (pH equals login (l/CH) and anincrease in the concentration in the hydroxyl ions all of which ions areavailable for reactions and for absorption by colloidal particles. Therelative concentrations of the hydrogen and hydroxyl ions and theircoefficients of absorption by the dispersed phase determine the amountsof separate ions absorbed by each unit colloidal particle and 125 thenature (positive, neutral or negative) and the magnitude of its charge.It is therefore possible by pH regulation to give the particles of sometypes of materials any desired degree of positive or of negative charge,especially if the 130 coefficients of absorption of the hydrogen andhydroxyl ions are large. The neutral particles have practically noBrownian motion, which results from mutual repulsion of moving chargedparticles, and such neutralized particles slowly 135 combine andflocculate out of solution. Particles with increasing positive ornegative charges increase in mobility up to 3 to '7 microns per secondper volt centimeter drop in applied E. M. F. and its stability or lackflocculation in the solution increases.

But other monoand polyvalent ions and the molecules are also absorbedalong with the hydrogen and hydroxyl ions in aqueous solutions and canbe therefore made to assist in charging or neutralizing the colloidalparticles while keeping the pH value at any desired figure to regulateother properties of the solution. For example, trivalent aluminumcations or phosphate anions can be used to add large numbers of positiveor 150 negative charges to particles or to neutralize opposite charges.Similarly, calcium, sulphate, arsenate, phthalate, tartrate, sulphonatedfatty acid ions and any other cations and anions can be used. By varyingthe degree of neutralization of any polyvalent base or acid thecolloidal particle can be surrounded by different concentrations of thefree base or acid and of the acid .or basic salts and of their ions andof the neutral salts and of their ions, all of which are absorbed inVarying degree and contribute to the electrical and physical propertiesof the colloidal particles and of the entire solution. Furthermore,neutral or ionized protective colloids like western larch galactan, gumarabic, rosin soap, sulphonated castor oil or ilsh oil soaps, vegetableoils, etc. may be added at the same time to form a coating or layeraround the colloidal particles to adsorb the surrounding ions andchemicals and to increase or decrease the stability. Naturally theconcentration of the buffer materials and of the protective colloidalmaterials can be increased while keeping the pH value or other electricfactors at ilxed values or at desired variable values. By all of thesemethods we can control separately and collectively each one of theimportant factors of contact potential between the particles andsolvent, surface tension, electrical conductivity, osmotic pressure,nature and degree of electric charge on the colloidal particle, pHvalue, viscosity, mobility of the colloidal particles, size of thecolloidal particles produced by dispersion, etc.; and we can therebyregulate the variable properties of both the dispersed phase and thedispersion medium of widely different liquid and solid colloidalsolutions. All these particles have an effect not only on the size ofthe particles that can be formed by dispersion in this and other colloidmills but on the properties thereof after dispersion. By the methods ofoperation and control I not only determine and regulate the propertiesof the colloidal solution itself but also the relation of suchproperties to the materials to be treated therewith. For example, I canregulate the properties of two colloidal solutions that are to be mixedwithout fiocculation on the one hand, or with resulting occulation onthe other hand when the charges on all the positive or negativeparticles are practically neutralized. Or I can properly control theproperties of colloidal solution extracted from, or used to coat orimpregnate, solid or fibrous products; for example, coating automobiletires and rainprooiing fabrics with rubber emulsions or impregnatingcross ties, telegraph poles, or the like with a creosote emulsion, ormakingextracts from various vegetable and animal tissues.

An example of this last process is the extraction of galactan fromwestern larch. When the western larch chips and sawdust are extractedwith water an aqueous mixture of galactan and tannin and perhaps othermaterials is obtained. If the chips or aqueous extracts are heated at-125 C. in solutions containing 1-2 percent of sulphuric acid, that isat a pH of about 1.7-1.4 or below, together with a decolorizing carbonor clay or silica gel or other similar agent when desired, the tanninand other coloring matters are ilocculated and can be easily filtered.'Ihe ltrate contains the residual galactan and also quantities ofgalactose and other materials formed by hydrolysis of the galactan andother constituents of the wood and extracts and by further heating allof the galactan can be converted to galactose. When it is desired toobtain galactan in the form of a solution or solid gum withoutcontamination with the hydrolysis products (galactose etc.) or withtannin materials the aqueous larch extract is treated with about 1percent of charcoal or bentonite or 'silica gel or other decolorizingagent when desired and with aluminum sulphate or chloride. 'I'he amountof the aluminum salt may vary froma few parts per million to a few partsper thousand of solution depending upon the amount of tannins andcolloidal material to be removed. 'I'he pH value of theentire solutionis now adjusted to cause the occulation of all the tannins, colloids,carbon or other decolorizing agent, and of the aluminum as hydroxide.Instead of an aluminum salt, fiocculated aluminum hydroxide may be usedas such and dispersed into the galactan solution by means of the colloidmill to adsorb the tannin and other materials. The best pH for theocculation of the aluminum hydroxide is about 5.8 but the adsorption ofother positive or negative ions or molecules of various materials by thenormally positive aluminum hydroxide may cause a variation of ya fewtenths one way or the other, depending upon the concentrations andadjustment of all the materials concerned. When the flocculate isfiltered off a clear, colorless solution of unhydrolyzed galactan isobtained with practically no soluble inorganic impurities. Byevaporation of this solution under vacuum or otherwise to preventdecomposition a thick tay or solid can be obtained, which can be used assuch or treated with alcohol to form a white powder. The galactan insolution is useful like gum arabic, etc., as a protective colloid toform stable emulsions of oils or solids, as an adhesive, and as acoating for mucic acid and the like in baking powder to delay theiraction with sodium bicarbonate. l 'Ihis mill and these processes arealso useful in making electrolytic condensers and alternating currentrectifiers and the like. When two plates of aluminum, iron, copper,tantalum or lead are immersed in iiuid or gel electrolytes m such asadjusted phosphate, borate, arsenate, etc. buffer solutions and anelectric current is passed alternately from metal to metal a deposit ofaluminum hydroxide, ferric hydroxide, etc., is formed as a dielectricfilm on each plate. The cacapcity of the condenser and its constancy canbe regulated by the adjustment of the pH and other electrochemicalfactors as follows. The solubility of the aluminum hydroxide film varieswith the pH and the amount of positive or negam tive ions adsorbed fromthe solution. At a pH of 4.5 to 6.5 and especially at about 5.8, thecapacity is comparativelyY constant because the film is very insoluble;but it dissolves slowly in a solution having a pH of 9 or 10 and thecapacity is V1M thereby increased when desired; e. g. from 0.1microfarad per sq. cm. surface to several times this value. By keepingthe pH value adjusted at the point of least solubility or most constantcapacity of the film very satisfactory condensers can be made withmanyfold the capacity of paper or mica condensers of the same metalsurface and with a breakdown voltage of 500 volts or more, dependingupon the applied E. M. F. when the films are formed. As the solutiongradually becomes cloudy from the disruption of colloidal particles fromthe lm and these charged particles migrate with the current to and fromthe iilm,thecolloidmillcanbeusedtodispersethem illm material such asaluminum hydroxide in the electrolyte and thereby saturate it before usefor forming and connecting the nlms on the plates. By this regulation ofthe pH value I can use comparatively dilute electrolytes such as l-2percent or less, with great advantage and with small power losses suchas 2-5 percent. Excellent rectiflers can be made for changing analternating to a direct current for charging storage bat. teries and forfurnishing the grid and lament current for radio installations and thelike. This is done by using a Nodon valve arrangement with lead andaluminum plates immersed in a phosphate or other suitable electrolytewith adjusted l5 pH value between 4 and 6. It can also be done (1) byforming a cell with lead and aluminum plates in succession andconnecting all the lead plates as one electrode, and then connectingalternate aluminum plates to form two other electrodes 2o comprising twosides of a Nodon valve; and (2) then using two equal inductances orchoke coils to replace the other two sides of a Nodon valve, the directcurrent connections being made at the lead plates and at the Junction ofthe choke coils, and the alternating current connections being made atthe other two corners, by drawing off the above described directcurrents through a series of inductances in parallel with capacities ofproper values to sift out the overtones, it is possible to obtainpractically a pure direct current of desired voltage and amperage. Byusing an interrupter with a 60 cycle alternating current and therebyproducing frequencies above the audible range and rectifying such highfrequencies, the pulses in the direct current are above audiofrequencies and do not disturb the'use of such direct current in placeof A and B batteries in radio communications. The same object may beaccomplished by rectifying the cycle alterz i nating current andconverting this direct current by means of an inductance, a condenserwhich may be an electrolytic one with regulated electrochemicalconditions, and a DeForest tube back into a sine wave alternatingcurrent with fref quencies below or above audible ranges, and thenrectifying this alternating current by means of an adjusted rectifier ofthe above types. Such a rectified direct current may still have pulsesif not filtered as above, but such pulses will be g; outside the audiblerange and will not be heard when used for lament and grid currents.

Having thus set forth my invention, I claim: 1. A colloid millcomprising a cylindrical case with a series of parallel grooves on theinside g surface of the case, each groove being in a plane perpendicularto the axis of the cylinder and having a sharp edge between such grooveand the next one, all grooves being parallel, and comprising a groovedcylindrical rotor rotating at high ;v speed in excess of 1,000revolutions per minute, each groove of the rotor having a sharp edgebetween such groove and th next one, the sharp edges of the grooves ofthe rotor tting between the sharp edges of the grooves of the case, andt" comprising an inlet and an outlet situated approximately 300 to 330from the inlet, and comprising two end plates and stumng boxes toenclose the liquids circulating through such mill, and comprising twobearings supporting such w shaft of such rotor and holding such rotor inany fixed position parallel to the axis of such case.

2. A colloid mill comprising a rotor adapted to be rotated at highspeed, a casing enclosing said rotor, said casing approaching said rotorcon- Losanna tinuously in the direction of its rotation for aconsiderable arc around said rotor and an inlet adjacent the portion ofsaid arc where said spacing is greatest and an outlet adjacent theportion of said arc where the spacing is least.

3. A colloid mill comprising means to exert a continuously increasingpressure upon material simultaneously with the subjection of thematerial to an increased centrifugal force, and thereby and therewith toan increased shearing stress, said means comprising a rotor and shaftadapted to be rotated at high speed and a casing having an inlet and anoutlet, said casing approaching said rotor more closely in the regionadjacent the outlet than at the inlet, said outlet and inlet beingseparated by a wall parallel to the shaft and close to said rotor andadapted to prevent fine material from passing with the rotor from saidoutlet to said inlet and crude material from passing directly from saidinlet to said outlet.

4. A colloid mill for disintegrating contained dispersions comprising ashaft and a rotor adapted to be rotated at high speed in the arc of flowof the dispersion, said rotor having grooves around the external surfacethereof and a casing enclosing said rotor, said casing having sharpridges which mesh into the grooves of the rotor, said casing having aninlet to a space between said rotor and vsaid casing and an outlet at apoint removed from the inlet, both inlet and outlet being generallyparallel to said rotor and shaft, said casing approaching said rotormore closely adjacent the outlet than at the inlet, and a baille wallsituated parallel to the shaft and close to the rotor and between theinlet and outlet.

5. A colloid mill comprising a generally cylindrical rotor adapted to berotated at high speed,

a generally cylindrical casing enclosing said rotor, an inlet runninglengthwise the casing substantially parallel to the axis of said rotorand admitting the material to be treated to the surface of said rotor ina illm whose plane is substantially parallel to the shaft of said rotor,and an outlet parallel to the axis of said rotor and located at a pointon the circumference of said casing removed from said inlet by more than180 in the direction of rotation of said rotor, whereby said generallycylindrical casing and rotor and inlet and outlet co-act to cause thetreated material to travel in circular arcuate paths whose planes areperpendicular to the rotor axis.

6. In a colloid mill, a high speed rotor, in a casing, the end walls ofthe casing being imperforate, and close to the rotor, the rotor beingcloser to the outlet than to the inlet, an inlet leading into the spacebetween the casing and rotor where said space is wide, and an outletleading from the space between the casing and rotor where the space isnarrow, and a dam between the inlet and the outlet to prevent directpassage of the fed-in material from the inlet to the outlet in adirection contrary to the direction of travel of the rotor, whereby allof said fed-in material must travel from a wide part of the spacesurrounding the rotor, to and through a narrow part thereof.

7. A colloid mill comprising a cylindrical case having circumferentialgrooves on its inner surface, having' a cylindrical rotor withcircumferential ridges adapted to mesh with said grooves on the case,and means for adjustably moving said case and rotor relatively to eachother in a 150 direction perpendicular to the axis of rotation, wherebythe space between the rotor and case is adjustable at its narrowestportion.

8. In a mill for producing suspensions and emulsions, the combination ofa generally cylindrical casing, a cylindrical rotor within said casingand in close relation therewith, uid inlet IUU

